碱蓬促生细菌的筛选、鉴定及其对盐碱胁迫下苜蓿种子萌发及幼苗生长的影响

Screening and identification of Suaeda salsa growth-promoting bacteria and their effects on alfalfa seed germination and seedling growth under salt-alkali stress

为了筛选碱蓬促生细菌,并研究其对盐碱胁迫下苜蓿种子萌发及幼苗生长的影响,试验采集较为健壮且无病虫害的碱蓬植株及其根际土壤,对其中的菌株进行分离、纯化,对分离菌株进行生化鉴定、16S rDNA基因序列分析和耐盐碱性分析,并研究各分离菌株对盐碱[NaCl、Na_(2)SO_(4)、NaHCO_(3)、Na_(2)CO_(3)物质的量的比为9∶1∶1∶9,浓度为0(不添加),50,100,150,200,300 mmol/L]胁迫下苜蓿种子发芽率、根长、芽长和鲜重的影响。结果表明:从碱蓬根际土壤及植株内共获得5株分离菌株,分别为JT2、JT4、JT8、JG1和JJ5;经生化鉴定、16S rDNA基因序列的分析后确定JT2、JJ5和JG1为沙雷氏菌,JT4为嗜麦芽寡养单胞菌,JT8为短小芽孢杆菌。当盐碱溶液浓度≥50 mmol/L时,JT2和JJ5生长受到抑制;当盐碱浓度≥100 mmol/L时,JT4生长受到抑制;当盐碱浓度≥150 mmol/L时,JG1生长受到抑制;当盐碱溶液浓度为50~150 mmol/L和300 mmol/L时,JT8生长受到抑制。当盐碱溶液浓度为50,100 mmol/L时,经各分离菌株处理的苜蓿种子发芽率和根长均显著高于对照(不加菌悬液的苜蓿种子,P<0.05);当盐碱溶液浓度为150 mmol/L时,经JT4处理的苜蓿种子发芽率和根长显著高于对照(P<0.05),经JJ5和JT8处理的苜蓿种子发芽率均显著高于对照(P<0.05),根长略高于对照(P>0.05),且经JT4处理的苜蓿种子发芽率和根长显著高于JJ5和JT8(P<0.05)。当盐碱溶液浓度为100 mmol/L时,经各分离菌株处理的苜蓿种子芽长均显著高于对照(P<0.05);当盐碱溶液浓度为150 mmol/L时,经JT4处理的苜蓿种子芽长显著高于对照(P<0.05),经JJ5和JT8处理的苜蓿种子芽长均略高于对照(P>0.05)。当盐碱溶液浓度为100 mmol/L时,经JT4、JJ5、JT2、JG1和JT8处理的苜蓿种子鲜重均显著高于对照(P<0.05);当盐碱溶液浓度为150 mmol/L时,经JT4、JJ5和JT8处理的苜蓿种子鲜重均显著高于对照(P<0.05),且经JT4处理的苜蓿种子鲜重显著高于JJ5和JT8(P<0.05)。说明5株分离菌株均为碱蓬促生细菌,其中JT4对盐碱胁迫下苜蓿种子萌发及幼苗生长的效果最佳。

In order to screen Suaeda salsa growth-promoting bacteria and to assess its effect on alfalfa seed germination and seedling growth under salt stress,robust and pest free suaeda plants and rhizosphere soil were collected,the strains were purified,isolated,identified,sequenced by 16 S rDNA and analyzed for salt and alkali tolerance(NaCl,Na_(2)SO_(4),NaHCO_(3) and Na_(2)CO_(3) was 9∶1∶1∶9 with a concentration of 0,50,100,150,200,300 mmol/L).At the same time,the effects of different strains on germination rate,root length,bud length and fresh weight of alfalfa seeds under salt-alkali stress were studied.The results showed that five strains were isolated from the rhizosphere soil and the plant of Suaeda salsa,which were JT2,JT4,JT8,JG1 and JJ5.JT2,JJ5 and JG1 were identified as Serratia,JT4 as Maltooligomonas maltophilia and JT8 as Bacillus parvus by biochemical identification and 16 S rDNA sequence analysis.The growth of JT2 and JJ5 was inhibited when saline-alkali concentration was higher than 50 mmol/L.The growth of JT4 was inhibited when saline-alkali concentration was≥100 mmol/L.The JG1 growth was inhibited when the saline-alkali concentration was≥150 mmol/L.The growth of JT8 was inhibited when the saline-alkali concentration was 50-150 and 300 mmol/L.When the concentration of salt-alkali solution was 50,100 mmol/L,the germination rate and root length of alfalfa seeds treated by various isolates were significantly higher than those of the control(without suspension,P<0.05).When the saline solution concentration was 150 mmol/L,the seed germination rate and root length of ALfalfa treated by JT4 were significantly higher than that of the control(P<0.05),the seed germination rate of alfalfa treated by JJ5 and JT8 were significantly higher than that of the control(P<0.05),and the root length was slightly higher than that of the control(P>0.05).The germination rate and root length of alfalfa treated by JT4 were significantly higher than those treated by JJ5 and JT8(P<0.05).When the concentration of saline solution was 100 mmol/L,the seed bud length of alfalfa treated by all isolates was significantly higher than that of the control(P<0.05).When the saline solution concentration was 150 mmol/L,the seed bud length of alfalfa treated by JT4 was significantly higher than that of the control(P<0.05),and that treated by JJ5 and JT8 was slightly higher than that of the control(P>0.05).When the concentration of saline solution was 100 mmol/L,the fresh weight of alfalfa seeds treated with JT4,JJ5,JT2,JG1 and JT8 was significantly higher than that of the control(P<0.05).When the saline solution concentration was 150 mmol/L,the fresh weight of alfalfa seeds treated with JT4,JJ5 and JT8 was significantly higher than that of the control(P<0.05),and the fresh weight of alfalfa seeds treated with JT4 was significantly higher than that of JJ5 and JT8(P<0.05).The results indicated that all the five isolates were Suaeda salsa growth-promoting bacteria,and JT4 had the best effect on alfalfa seed germination and seedling growth under saline-alkali stress.